SAN DIEGO – A private fishing boat entering San Diego Bay was loaded with nearly half a ton of marijuana, U.S. Customs and Border Protection officials said Monday.

Agents aboard a speed boat spotted the 21-foot vessel about 6 p.m. Saturday at the entrance to the bay, officials said.

The boat was riding suspiciously low in the water.

Agents stopped the vessel to question a couple on board. A 20-year-old woman and a 40-year-old man, both U.S. citizens who live in Phoenix, gave authorities different accounts during questioning, officials said.

Agents checked the boat further with a drug-sniffing dog, which signaled to the rear of the vessel.

Hidden underneath the deck of the boat were 221 packages of marijuana weighing 944 pounds, agents said. The packages were sealed underneath the deck with fiberglass, authorities said.

The drugs and the boat were seized and the pair turned over to Immigration and Customs Enforcement officers.